Notes · LoRa · Solar
Solar LoRa sensors that smell bushfires
A sensor about the size of a TV remote, strapped to a tree, can now smell a bushfire while it is still smouldering. It runs on a solar cell the size of a sticky note and reports over LoRa.
Bushfire season is starting, and this spring's national outlook from AFAC lists parts of South Australia among the areas with heightened fire potential (AFAC Spring 2026 outlook). So it's a good time to look at one of the cleverest uses of LoRa and solar we've seen: Dryad's Silvanet wildfire sensor.
Why smell beats sight
Most fire detection waits for something visible. Lookout towers and cameras need smoke, and satellites need heat. By the time a fire shows up on any of them, it may already be spreading.
Silvanet works earlier. Before flames appear, burning wood gives off gases such as hydrogen and carbon monoxide. Dryad says its sensor can detect these at parts-per-million levels, often within the first hour of ignition (Silvanet datasheet). That's the smouldering stage, when a fire is still small enough to put out quickly.
How the Silvanet sensor works
Each sensor is mounted directly on a tree and acts as an "electronic nose" (Dryad).
- Sensing: a Bosch BME688 gas sensor, plus temperature, humidity and air pressure. On-board AI compares the gas readings against the signature of a smouldering fire to cut false alarms.
- Power: a 6 × 6 cm solar panel charges supercapacitors, not batteries. With no lithium cells, the sensor won't add fuel or toxic waste to a forest. Dryad rates it for 10–15 years without maintenance.
- Radio: data goes out over LoRaWAN. The datasheet lists the AU915 band used in Australia (datasheet).
- Network: solar-powered mesh gateways relay messages through the forest to a border gateway with an internet link. One gateway typically serves about 100 sensors (The Things Industries).
The low-power design comes from ST's STM32WL chip, which combines a microcontroller and LoRa radio. ST and Dryad tuned it to run on a forest floor's worth of sunlight (ST blog).
Is it in Australia?
Dryad opened an Australia and New Zealand office in Macquarie Park, NSW, in March 2025. Its local partners include Thinxtra and Indigenous Industries Australia (Dryad announcement). The system has been installed in countries including Greece, Spain and South Korea. We haven't found a named Australian deployment yet, so if you know of one, let us know.
The reality check
This is promising technology, not a silver bullet.
- Density. One sensor typically covers about one hectare (ST blog). A 100 km² forest would need around 10,000 of them.
- Where it fits. It suits high-value spots: the edge of a town, a plantation, a power-line corridor. It won't cover the whole Mount Lofty Ranges.
- Claims. Detection times and the comparison with towers and satellites come from Dryad itself. Independent field results in Australian bush will be the real test.
Coming next: build a mini version
The best part for makers is that the BME688 at the heart of Silvanet is a hobby-grade part. In our next Notes post, we'll build a solar LoRa air-quality and weather node in MicroPython (programmed with Thonny):
- A Raspberry Pi Pico or ESP32 running MicroPython
- A BME688 (gas, temperature, humidity, pressure) or a BME280 if you only want weather
- A 915 MHz LoRa module for the ANZ band
- A small solar panel, Li-ion cell and charger in a weatherproof box
It won't be a fire alarm. It's a learning project to watch your own backyard's air and weather, and to see how far LoRa reaches across the Hills.
Always use the CFS website, the Alert SA app and ABC Radio. A homemade sensor is never a substitute.
Sources
Checked October 2026.